Condensate circulation control for boiler plants



Sept. 19, 1933. c. H. SMOOT 1,927,506

couvsnsms cmcumwxon common FOR 50mm rumws Filed May 28, 19:50 2 Sheets-Sheet 1 INVENTOR (Zak/es -J r7oof Sept. 19, 1933. Q H SMOQT 1,927,506

CONDBNSATE CIRCULATION CONTROL FOR BOILER PLANTS Filed May 28, 1930 2 Sheets-Sheet 2 INVENTOR. Char/e5 H. 501002 ATTORNEYS Patented Sept. 19, 1933 PATENT OFFICE.

' CONDENSATE CIRCULATION CONTROL FOR BOILERPLANTS Charles H. Smoot, Maplewood, N. J.; Katherine Smoot executrix of said Charles H. Smoot,

deceased Application May 28,.11930. Serial No. 456,782 7' Claims. .(ol. 60- 94) My present invention-relates to the regulation of- 'thesupply' of condensate-tofeed Water pumps of a boiler plant and comprises a novel system arranged to correct for variations in the circulat'ingsystem due to changes in the load upon the turbines and to regulate the pressure in the condensate pump discharge header to avoid formation of steam in the suction of the'feed waterpumps. The regulating system which I have devised insures a smooth operation of the variousauxiliaries of a feed water system and soregulates the addition of make-up water to the system as to insure economyancl safety of operation of each pumping unit of a plant.

' More specifically, my invention comprises a regulator responsive to the level of the'water in the hot well and arranged to control valves in the make-up and-draw-ofi lines leading from the distilled water supply anda second regulator'rev Z sponsive to the condensate pump discharge pres- Fig. 2'is a view illustrating a modified form of' 'oneelement of one ofthe regulators-of Fig.1.

Referring to Fig. 1,.ahot well 1, which may be onei'of a plurality of similar wells of a boiler plant, receives condensate through 'a'pipe 2 from one of'theturbines (not'shownl' ofthe plant. 'A constant' speed pump'3' withdraws condensate. from the hot-well anddelivers the same as feedwater through the header 4 to theboiler feedpumps. Branching from the header 4 is the draw-off line 5 connecting withthe make-up line 6 leading to the distilled water tank '7. The arrangement above describedforms no part of my invention but is an example of the type offeed water systemttowhich my invention may be advantageously' applied; To insure asubstantiallyuniform waterlevelin the Well 1- and consequent smooth operation of the entire system. I provide a regulator fi arranged to control valves 9 and min lines 5 and 6, respectively, Regulator 8' is preferably of the anti-hunting type andcomprises a pivoted balancelever 11 adapted upon displacement to vary the pressure of auxiliary *power fluid supplied-to a chamber 12 by-control of the position of a throttle valve 13 connected to the-lever 11 and 'controllingtheleakage-'of-fiuid i from' chamber 12. A" diaphragm f 14; dividing a "mentor the piston of the pilot valve 34 in a direcates' to close the'pilot valve byrockin'g of lever casing 15 into two ehambers'lfi and 1'7, is connected to one end of lever 11 by means of a rod 18 and transmits to the lever a force varying with the differential of the pressures in these cham: hers. A manually adjustable spring 19 connected to the other end of the leverll adds a force to the lever in a .direction to oppose that due to the pressuredifierential. Chamber 16' is connected by means of a pipe 20 to the hot well 1 beneath the level of the water therein andreceives therefore a pressure varying with the height of the water in the well and with the pressure acting upon the surface thereof. Chamber 17 is connected by means of a pipe 21 with a constant level device 22 to receive therefrom a pressure varying only with the pressure above the water in the hot well. The device 22 comprises a chamber divided by a partition 23 into-two compartments, one of which is connectedwith the upper endof the hot Well-by means of a pipe 24, and .5 the'other of which is filledwith water up to the top of the partition 23 by water supplied through a pipe25.- Pipe 21 is connected to the compartment containing'water at the constant level of the partition 23 whereby chamber 17 receives a con 8. stantpressure equal to the constanthead of Water in this compartmentand in pipe-21 and a variable pressure equal-to' that above the water in the hotwell. The pressure differential between chambers 16and 17 will thus vary solely with the water level in the hot well,- decreasing with increasing-water level, and increasing with decreasing water level.

Returning nowto regulator 8, movement of lever 11 under the above described forces is arrangedto cause -moveme'nt of a power piston 26 by variation of the pressure in chamber 12; piston 26 forming the-movable upper wall of this chamber; and biased to its lowermost position by aweight 27. A piston-rod 28 carried-by'piston 9 26 has linked thereto a power arm 29 pivoted on a fix'edpart of the regulator. A-fioatinglever 30 is connected to powerarm 29 by meansof a link 31 and'is likewise connected to' the piston 'rods- 32am 3-3 of a pilot valve 34*and relay cyl- 'in'der3'5, respectively. The arrangement is such that a clockwise movement of arm 29 occasioned by upward movement of piston 26 causes movetion to supplypressure fluid beneath the piston 05 36 of relay cylinder 35 by connecting supply pipe 37 with pipe 38ancl to drain the upper part 'ojf relay-cylinder35 by connecting pipe 39 with the drain pipe 40. Movement of the piston 36 operabout its connection with link 31. Conversely, counterclockwise rotation of arm 29 occasioned by downward movement of piston 26 causes opening of pilot valve 34 in a direction to cause downward movement of piston 36 followed by closure of the pilot valve.

N Movement of piston 36 is arranged to successively operate valves 9 and 10 in the following manner. The stem 41 of valve 9 is linked to one end of a pivoted lever 42, the other end of which is bifurcated and carries a 'pin43 slidable in a slot 44 in the lower end of the rod 33. A cross bar 45 fastened to the rod 33 and connected to lever 42 by springs 46 bias lever 42 toward closed position of valve 9. Similarly the upper end of rod 33 is provided with an elongated slot 47 in which is movable a pin 48 connected betweentwo parts of a bifurcated lever 49, movement of which about its pivot 50 operates the valve 10. A member 53 mounted on rod 33 and connected to lever 49 by springs 54 biases valve 10 toward closed position.

With piston 36 in the mid-position illustrated,

T valves!) and 10 are both closed, with pins 43 and 48 in contact with the inner ends of slots 44 and 47 respectively. Downward movement of the piston 36 causes extension of springs 54 but no movement of lever 49 as valve 10 being already closed,

stem 52 prevents downward movement of lever 49. The downward movement of rod 33 causes tipping of lever 42 and gradual opening of valve 9. Conversely, upon return of piston 36 to midposition, valve 9 is closed and upon continued upward movement of the piston, springs 46 are extended, valve 9 remains closed and valve 10 is gradually opened loy clockwise rotation of lever 49.

Instead of the above described simple arrangement, other means for successively operating valves 9 and 10 upon movement of piston 36as by lost motion devices and quadrant gearing could be as readily employed.

The regulating system above described operates upon a change in water level in hot well 1 3 I as follows: Assuming an increase in level, occasioned by turbine load variations, and assuming valves 9 and 10 both closed, as shown, the pressure diiferential acting upon diaphragm 14'is reduced and spring 19 thereupon overbalances the force transmitted to lever ll by rod 18.

Lever 11 then tips in a counter clockwise direction, slightly raisingvalve 13 and thereby reducing the pressure in chamber 12. Weight 27 then forces piston 26 downwardly and arm 29 is tipped in a counterclockwise direction, causing operation of pilot valve 34 in a direction to connect pipes 37 and 39 and to connect pipes 38 and 40, whereby pressure fluid is supplied above piston 36 and drained from below this piston. Piston 36 thereupon descends-causing partial opening of valve 9 and closure of pilot valve 34. The

opening of valve 9 increases the withdrawal of water from the hot well and thereby lowers the level therein until balance is re-established upon the lever 11 of, regulator 8. The water drawn off through pipe 5 is returned to the tank '7 until again required in the system. Should the valve 9 not be sufficiently opened by the above operation, lever 11 will remain unbalanced and the operation will be repeated until the level in the hot well is that desired. If, on the other hand, the level in the hot well drops to too low a value, lever 11 will be tipped in a clockwise direction to increase the pressure beneath piston 26 and to therebycause operation of the pilot valve in a direction to cause upward movement of relay variation in level before coming into operation, while insuring that the level will be held between fixed maximum and minimum limits.

In Fig. 2 I have illustrated the system arranged for permitting this level variation in the hot well. Fig. 2 differs from Fig. 1 only in that parts are added to regulator '8. These parts comprise a cross bar'55 rigidly secured to the piston rod 28 of the regulator and a weight 56 partly carried by oneendv of the bar 55 and partly suspended from the lever 11. In operation, the tension of spring19 is so adjusted that with the level in the hot well mid-way between the desired minimum and maximum levels, about one-half of the weight 56 is active upon the lever lland the piston 36 of the relay cylinder is in its mid-position with valves 9 and 10 both closed If now the level in the hot well rises, the differential pressure acting on diaphragms 14 decreases tend; ing to cause tipping of lever 11 in a counter clockwise direction. This decreases the pressure beneath piston 26, which, except for the provision of weight 56, would descend sufiiciently to open pilot valve 34. The moment, however, that pistonv 26 starts downward, the support of weight 56 by bar 55 is removed so that lever 11 is immediately restored to balance and the pilotvalve is prevented from operating. It will thus be seen that not until the level increase in the hot well is of such. a magnitude that the decrease in the pressure differential on diaphragm 14 more than offsets the additional force added to the lever by the .removal of bar 55 from contact with weight 56 will the pilot valve be opened. Conversely, a decrease in water level, increasing the pressure difierential upon diaphragms 14 will merely operate to cause bar 55- to support the entire weight 56 and will not cause operation of the pilot valve until the level is'so low that the pressure differential'alone will overpower the force of spring 19 upon lever 11. v The magnitude of weight 56 is, of course, chosen according to the range in water level variation desired; the smaller the weight the smaller the range of level variation before operation of the valves9 and 10.

Preferably I' combine with the regulationfresponsive to the hot well level, a regulator arranged to maintain the pressure inthe condensate discharge header above a predetermined value to prevent formation of steam in the suction of the feed water pumps. In the drawings such a regulator is shown at 57 andcornprises a structure substantially similar to regulator 8 and arranged to directly operate a valve 58 in the draw-off line 5 in response to the pressure in the header 4 as transmitted by a pipe 59 to a chamber 60. Chamber 60 is closed by a diaphragmfil connected to the balance lever.62 of the regulator by a rod 63. A compression spring-64 acting beneath the diaphragm 61 opposes movement thereof upon increase in pressure in chamber60.

The operation of regulator 57 is substantially similar to that of regulator 8. Upon decrease-in pressure in header 4, spring 64 tips lever 62 in a direction to decrease the pressure beneath the weighted power piston of the regulator and to thereby cause counter clockwise rotation. of the power arm in a direction to close valve 58 and to thereby. increase the pressure delivered by pump 3. As regulator 57 operates a valve in series with the valve 9 in the draw-off line, it will be noted that it operates solely to insure that regulator 8 will not reduce the pressure in the condensate header 4 by too great an amount. During normal operation of the system, when valves 9 and 10 are closed, regulator 5'7 is, of course, ineffective, but is effective only at such times as there is the danger of too'low a pressure in the header 4; viz., when valve 9 is open.

I have now described my complete regulating system for the pumping units of a boiler plant as applied to the regulation of a single unit. When additional units are provided, I propose to regulate each in response to the level in the hot well thereof. Obviously various changes in the construction of the regulators and in the arrangement thereof could be made without departing from the broad principles of my invention which are concerned primarily with hot well level re-' sponsive means for controlling the make-up and draw-off of water to the hot well of a boiler feed water unit.

The means described for permitting variation in water level throughout a predetermined range are susceptible of use with other than level regulators, but no claim is made herein for such means except in combination with hot well level regulation.

I claim 1. In a feed water unit of a plant including a hot well receiving condensate from steam utilizing devices and supplying the same under pressure as feed water toa condensate header, and make-up and draw-off lines from said hot well and condensate header respectively, a regulating system for the unit comprising valves in said make-up and draw-off lines, a regulator for said valves responsive to the level of the water in said hot well, a second valve in said draw-off line and a regulator therefor responsive to the pressure in said condensate header.

2. In combination with a hot well and make-up and draw-off lines therefrom, a regulating systern including a valve in each of said lines, a

well, and means for operating said valves successively by continued operation of said regulator due to unbalance of forces upon said lever.

3. The combination according to claim 2 wherein operation of said valves is prevented during a predetermined range of water level variation in said well by means including a weight normally partially suspended from said lever and adapted to be entirely suspended or removed therefrom before operation of said valves by said regulator.

4. The combination according to claim 2 including a condensate header receiving water from said well, a second valve in said draw-off line and a regulator responsive to the pressure in said header adapted to close said second valve upon decrease in said header pressure.

5. In a feed water unit of a plant including a hot well receiving condensate from steam utilizing devices and supplying the same under pressure as feed water to a condensate header, a regulating system for said unit comprising in combination means responsive to the level of water in said well adapted to maintain any desired water level therein and means responsive to the pressure in said header adapted to maintain said pressure above a desired minimum.

6. Incombination with a hot Well and make-up and draw-off lines therefrom, a valve in each of said lines, a relay cylinder provided with a piston and a'piston rod, biasing means tendingto hold said valves in closed position, lost motioncon- .necting means between said piston rod and said 7. The combination according to claim 6 including means associated with said regulator adapted to prevent movement of said piston except when said water level falls below a predetermined minimum or exceeds a predetermined maximum level.

CHARLES H. SMOOT. 

